This invention relates to window awnings and more particularly to adjustable window awnings.
Window awnings are used to protect buildings, including building interiors, from excessive gain of solar heat through windows, and also as architectural elements to enhance aesthetic appeal of building exteriors. Shading windows with awnings is one of the most popular methods of increasing energy efficiency of buildings. By lowering temperature inside the building during the air conditioning season, awnings create savings in cooling energy. According to a 2007 study by the University of Minnesota entitled “Awnings in Residential Buildings,” awnings may reduce consumption of cooling energy by up to 69% and peak electricity demand by up to 49%, depending on the building location and some other factors.
During the heating season, however, window awnings may block desirable passive gain of solar heat, offsetting energy savings achieved during the cooling season. Therefore, to achieve the highest energy savings, it is advisable to remove or retract window awnings during the period when the building needs to be heated. Because removing awnings for the heating season is inconvenient and could be expensive, it is preferable to use awnings that may be retracted or adjusted to allow desirable solar heat to reach the building interior through windows.
Such retractable or adjustable window awnings are well known in the industry and usually are made of fabric. A retractable fabric awning is retracted by rolling the fabric up onto a roller rotatably attached to the building. Even though retractable fabric awnings have been in use for decades, they are not sufficiently durable and require periodic replacement of the fabric. Fabric colors are prone to fading, reducing the aesthetic appeal of such awnings.
Also known are retractable or adjustable rigid awnings. An example of such adjustable awnings is described in U.S. Pat. No. 2,791,009 to Wagner. It is a louver type awning where louvers are operated by a link mechanism. Among the disadvantages of such awning is the existence of an excessive number of movable parts subject to weather elements, which makes it prone to malfunction. Also, such awning cannot be retracted for the heating season and therefore inevitably creates shade when it is not needed. A collapsible rigid awning is described in U.S. Pat. No. 6,202,363 to Chang. It may be collapsed when shade is not required, however its operating mechanism is complicated, consisting of many movable parts subject to weather elements, and also is prone to malfunction. In addition, when in the collapsed position, such awning requires substantial additional side space approximately equal to the length of its panels. Another type of retractable rigid awnings is available on the market in the form of roll-up awnings. Such awning consists of narrow aluminum strips connected to each other with ropes or bands and is retracted by rolling these strips up onto a roller, similarly to retractable fabric awnings. This design does not allow for any side panels that may be desired, has many small movable parts and requires constant tension to be applied to the connecting ropes or bands to maintain the awning in a taut condition, which reduces the awning's durability. An adjustable sunshade is described in U.S. Pat. No. 6,421,966 to Braunstein, et al. The sunshade is adjustable only at the time of its installation and creates shade during the heating season, thereby reducing energy savings obtained during the cooling season.
All of the above mentioned known retractable or adjustable window awnings provide no energy savings benefit during the heating season. Even when retracted or adjusted to prevent or reduce undesirable shading, they continue to age and deteriorate without providing any benefits.
An awning design that aims at providing an opportunity to use the awning as both a shading device and a sunrays reflection device that would aid in heating the interior of the building is described in U.S. Pat. No. 4,309,981 to Briggs, et al. In this design, the procedure to switch the awning function from shading to heating is cumbersome and requires direct access to the awning's canopy from the outside, but adjustment of the canopy's angle of inclination, on the contrary, may only be made from the inside of the building, which requires serious modifications of an existing window. Another embodiment of the same invention also allows canopy adjustment to be performed only from the inside requiring extensive modifications of an existing window.
Another combination window awning and solar heat unit is provided in U.S. Pat. No. 4,043,316 to Arent. In this combination unit, the lower part of the window is continually closed during the hot season, reducing the amount of daylight entering the building. The awning may be adjusted only by direct manual access from the outside. During the cold season, snow and ice will accumulate behind the upper awning panel when it is rotated up into its heating position. Neither of these last two inventions allows for the entire process of changing the awning function between shading and heating to be motorized.